Zenodo (CERN European Organization for Nuclear Research), Jun 5, 2023
In recent years, several new applications of SiC (both 4H and 3C polytypes) have been proposed in... more In recent years, several new applications of SiC (both 4H and 3C polytypes) have been proposed in different papers. In this review, several of these emerging applications have been reported to show the development status, the main problems to be solved and the outlooks for these new devices. The use of SiC for high temperature applications in space, high temperature CMOS, high radiation hard detectors, new optical devices, high frequency MEMS, new devices with integrated 2D materials and biosensors have been extensively reviewed in this paper. The development of these new applications, at least for the 4H-SiC ones, has been favored by the strong improvement in SiC technology and in the material quality and price, due to the increasing market for power devices. However, at the same time, these new applications need the development of new processes and the improvement of material properties (high temperature packages, channel mobility and threshold voltage instability improvement, thick epitaxial layers, low defects, long carrier lifetime, low epitaxial doping). Instead, in the case of 3C-SiC applications, several new projects have developed material processes to obtain more performing MEMS, photonics and biomedical devices. Despite the good performance of these devices and the potential market, the further development of the material and of the specific processes and the lack of several SiC foundries for these applications are limiting further development in these fields.
Background: Renal denervation with radiofrequency ablation has become an accepted treatment for d... more Background: Renal denervation with radiofrequency ablation has become an accepted treatment for drug-resistant hypertension. However, there is a continuing need to develop new catheters for high-accuracy, targeted ablation. We therefore developed a radiofrequency bipolar electrode for controlled, targeted ablation through Joule heating induction between 60 and 100 °C. The bipolar design can easily be assembled into a basket catheter for deployment inside the renal artery. Methods: Finite element modeling was used to determine the optimum catheter design to deliver a minimum ablation zone of 4 mm (W) × 10 mm (L) × 4 mm (H) within 60 s with a 500 kHz, 60 Vp-p signal, and 3 W maximum. The in silico model was validated with in vitro experiments using a thermochromic phantom tissue prepared with polyacrylamide gel and a thermochromic ink additive that permanently changes from pink to magenta when heated over 60 °C. The in vitro ablation zone closely matched the size and shape of the simulated area. The new electrode design directs the current density towards the artery walls and tissue, reducing unwanted blood temperature increases by focusing energy on the ablation zone. In contrast, the basket catheter design does not block renal flow during renal denervation. Conclusions: This computational model of radiofrequency ablation can be used to estimate renal artery ablation zones for highly targeted renal denervation in patients with resistant hypertension. Furthermore, this innovative catheter has short ablation times and is one of the lowest power requirements of existing designs to perform the ablation.
Semiconductor Science and Technology, Nov 18, 2003
The effective carrier density in porous silicon carbide is measured to be 40 times less than that... more The effective carrier density in porous silicon carbide is measured to be 40 times less than that in the starting material. An idea is proposed which relates the reduction in carrier density to some compensation effect. It is proposed that donor dopants are compensated by deep-level surface-localized, acceptor-like states appearing due to the large internal surface area developed as a result of pore formation in crystalline SiC. The estimated density of trapped electrons per unit internal surface area, 5 × 10 12 cm -2 , is quite reasonable for the density of deep-level states at the SiC surface.
ABSTRACT A continuous glucose sensor employing radio frequency (RF) signals has been developed us... more ABSTRACT A continuous glucose sensor employing radio frequency (RF) signals has been developed using the biocompatible material Silicon Carbide (SiC). Unlike biosensors that require direct contact with interstitial fluids to trigger chemical reactions to operate, this biocompatible SiC sensor doesn't require a direct interface. The sensing mechanism is based upon a shift in resonant frequency as a function of change in glucose levels which electrically manifests itself as a change in blood permittivity and conductivity. For invivo applications the antenna sensor needs to operate inside the body environment, and it has been determined that the best operational location of this biocompatible SiC biosensor is within fatty tissue in close proximity to blood vessels. To test the sensor as a function of glucose level, measurements using synthetic body fluid (SBF), which is electrically equivalent to blood plasma, and pig blood were performed. Changes in sensor performance to varying glucose levels were measured and a shift in resonant frequency to lower values observed with increasing glucose level. In-vitro sensor performance demonstrated that the sensor showed a dose dependent response to glucose concentration from 120 mg/dl to 530 mg/dl. A shift of 40 MHz and 26 MHz for blood mimicking liquid and pig blood was observed corresponding to 97 KHz and 67 KHz shift per 1 mg/dl change in blood glucose.
Atomic layer deposited (ALD) Pb(Zr,Ti)Ox (PZT) ultra-thin films were synthesized on an ALD Al2O3 ... more Atomic layer deposited (ALD) Pb(Zr,Ti)Ox (PZT) ultra-thin films were synthesized on an ALD Al2O3 insulation layer on 4H-SiC substrate for metal-ferroelectric-insulator-semiconductor (MFIS) device applications. The as-deposited PZT was amorphous but crystallized into a perovskite polycrystalline structure with a preferred [002] orientation upon rapid thermal annealing (RTA) at 950 °C. The capacitance-voltage and current-voltage characteristics of the MFIS devices indicate carrier injection to the film induced by polarization and Fowler-Nordheim (FN) tunneling when electric field was high. The polarization-voltage measurements exhibited reasonable remanent and saturation polarization and a coercive electrical field comparable to that reported for bulk PZT. The piezoresponse force microscope measurements confirmed the polarization, coercive, and retention properties of ultra-thin ALD PZT films.
ABSTRACTWe report on the growth and crystal quality of CVD epitaxial layers grown on porous SiC (... more ABSTRACTWe report on the growth and crystal quality of CVD epitaxial layers grown on porous SiC (PSC) substrates. A layer of porous SiC was fabricated by surface anodization of commercial 4H and 6H-SiC (0001)Si face off-axis wafers. The 4H and 6H-SiC epilayers were grown on porous SiC (PSC) substrates using atmospheric pressure CVD at 1580°C and a Si to C ratio of 0.3. Results of X-ray diffraction, RHEED, SEM and AFM characterization demonstrated good surface quality of the films grown on porous material. PL data indicate a greatly improved defect structure in the epi layers grown on PSC as compared to control samples. Preliminary etch pit experiments to estimate the dislocation density indicate a three-fold reduction in defect density in the epi material grown on PSC substrates as compared to epi grown conventional substrates.
We have studied the electroreflectance (ER) spectra of n- and p-type 4H–SiC polytype samples from... more We have studied the electroreflectance (ER) spectra of n- and p-type 4H–SiC polytype samples from 3 to 6.5 eV. The fundamental band gap and higher lying critical points are measured at room temperature. For this polytype, we observe band-gap narrowing in one of the structures with higher doping concentration.
We report on non-contact and non-destructive spatially resolved characterization of traps and lum... more We report on non-contact and non-destructive spatially resolved characterization of traps and luminescence centers in vanadium-free semi-insulating 6H-SiC. Two optical techniques were employed: photoluminescence (PL) mapping and thermally stimulated luminescence (TSL) imaging on SiC wafers. PL and TSL topography reveal inhomogeneity at the periphery regions of the wafers. Low-temperature PL spectra show broad bands with the maxima at 1.75eV and 1.2eV, including a sharp zero-phonon line at 1.344eV. The TSL glow curves at T>80K show different peaks in the visible and infrared bands. The luminescence spectrum of the 105K TSL peak replicates 1.75eV band, while the 120K peak corresponds to the 1.2eV band. Additionally, the high temperature TSL peak at 210K shows an excellent match with 1.344eV zero phonon line. The trap energies of different peaks are calculated. We discuss a model of complex defects composed of closely spaced electron (hole) trap and UD3 defect.
Core–shell Si/SiC nanostructures appear as promising building blocks for sensing applications, th... more Core–shell Si/SiC nanostructures appear as promising building blocks for sensing applications, thanks to the high chemical stability of SiC coupled with the semiconducting properties of Si. In order to optimize the fabrication process of such structures, Si nanowires were coated with a thin SiC layer, and integrated as back-gated field-effet transistors. Two approaches for the fabrication of the SiC shell were then investigated. The first approach involves chemical vapor deposition of amorphous SiC on Si nanowires, without the need for masking; the second approach involves carbonization of Si surfaces to produce a thin crystalline SiC layer, but requires a larger thermal budget. The resulting structures were analyzed using high-resolution transmission electron microscopy (HR-TEM), and the devices were characterized electrically. Electrical characterization shows that the carbonization approach induces a dramatic decrease in drain-to-source current associated with gate leakage, whereas the electrical performances were preserved in the case of chemical deposition.
A 4H-SiC epitaxial growth process has been developed in a horizontal hot-wall CVD reactor using a... more A 4H-SiC epitaxial growth process has been developed in a horizontal hot-wall CVD reactor using a standard chemistry of silane-propane-hydrogen, producing repeatable growth rates up to 32 μm/h. The growth rate was studied as a function of pressure, silane flow rate, and growth time. The structural quality of the films was determined by X-ray diffraction. A 65 μm thick epitaxial layer was grown at the 32 μm/h rate, resulting in a smooth, specular film morphology with occasional carrot-like and triangular defects. The film proved to be of high structural quality with an X-ray rocking curve FWHM value of the (0004) peak of 11 arcseconds.
ABSTRACTPendeo Epitaxy is a type of Lateral Epitaxial Overgrowth (LEO) that instead of using a di... more ABSTRACTPendeo Epitaxy is a type of Lateral Epitaxial Overgrowth (LEO) that instead of using a dielectric buffer layer, uses an etched substrate to grow laterally without an interface layer. We report the first successful growth of 3C-SiC on Si using Pendeo epitaxy. Rectangular stripes of 3C-SiC on (100) Si substrates were fabricated, along both the [110] and [100] directions. Pendeo epi was only observed for columns parallel to [001], indicating a preferred growth facet for Pendeo epi of 3C-SiC on Si. SEM and TEM investigations were performed to assess the material quality of the Pendeo 3C-SiC material. Films were grown for 60 min at 1310°C and film coalescence was achieved without evidence of voids where the growth fronts joined. TEM data indicate not only the growth of vertical and lateral 3C-SiC on the 3C-SiC seed layer but direct nucleation of 3C-SiC on the exposed Si columns side wall and trench bottom, despite the lack of a carbonization procedure. The quality of the Pendeo 3C-SiC film appears to be of high quality indicating that Pendeo epi of 3C-SiC on low-cost, large-diameter Si substrates may prove to be a cost effective way to grow device-grade SiC layers on Si substrates for device applications.
Page 1. Photoluminescence and Thermally Stimulated Luminescence in Semi-Insulating SiC Yu. M. Sul... more Page 1. Photoluminescence and Thermally Stimulated Luminescence in Semi-Insulating SiC Yu. M. Suleimanov 1 , S. Lulu 1 , I. Tarasov 1 , S. Ostapenko 1 , VD Heydemann 2 , MD Roth 2 , O. Kordina 2 and MF MacMillan 2 andS. E. Saddow 1 . ...
Zenodo (CERN European Organization for Nuclear Research), Jun 5, 2023
In recent years, several new applications of SiC (both 4H and 3C polytypes) have been proposed in... more In recent years, several new applications of SiC (both 4H and 3C polytypes) have been proposed in different papers. In this review, several of these emerging applications have been reported to show the development status, the main problems to be solved and the outlooks for these new devices. The use of SiC for high temperature applications in space, high temperature CMOS, high radiation hard detectors, new optical devices, high frequency MEMS, new devices with integrated 2D materials and biosensors have been extensively reviewed in this paper. The development of these new applications, at least for the 4H-SiC ones, has been favored by the strong improvement in SiC technology and in the material quality and price, due to the increasing market for power devices. However, at the same time, these new applications need the development of new processes and the improvement of material properties (high temperature packages, channel mobility and threshold voltage instability improvement, thick epitaxial layers, low defects, long carrier lifetime, low epitaxial doping). Instead, in the case of 3C-SiC applications, several new projects have developed material processes to obtain more performing MEMS, photonics and biomedical devices. Despite the good performance of these devices and the potential market, the further development of the material and of the specific processes and the lack of several SiC foundries for these applications are limiting further development in these fields.
Background: Renal denervation with radiofrequency ablation has become an accepted treatment for d... more Background: Renal denervation with radiofrequency ablation has become an accepted treatment for drug-resistant hypertension. However, there is a continuing need to develop new catheters for high-accuracy, targeted ablation. We therefore developed a radiofrequency bipolar electrode for controlled, targeted ablation through Joule heating induction between 60 and 100 °C. The bipolar design can easily be assembled into a basket catheter for deployment inside the renal artery. Methods: Finite element modeling was used to determine the optimum catheter design to deliver a minimum ablation zone of 4 mm (W) × 10 mm (L) × 4 mm (H) within 60 s with a 500 kHz, 60 Vp-p signal, and 3 W maximum. The in silico model was validated with in vitro experiments using a thermochromic phantom tissue prepared with polyacrylamide gel and a thermochromic ink additive that permanently changes from pink to magenta when heated over 60 °C. The in vitro ablation zone closely matched the size and shape of the simulated area. The new electrode design directs the current density towards the artery walls and tissue, reducing unwanted blood temperature increases by focusing energy on the ablation zone. In contrast, the basket catheter design does not block renal flow during renal denervation. Conclusions: This computational model of radiofrequency ablation can be used to estimate renal artery ablation zones for highly targeted renal denervation in patients with resistant hypertension. Furthermore, this innovative catheter has short ablation times and is one of the lowest power requirements of existing designs to perform the ablation.
Semiconductor Science and Technology, Nov 18, 2003
The effective carrier density in porous silicon carbide is measured to be 40 times less than that... more The effective carrier density in porous silicon carbide is measured to be 40 times less than that in the starting material. An idea is proposed which relates the reduction in carrier density to some compensation effect. It is proposed that donor dopants are compensated by deep-level surface-localized, acceptor-like states appearing due to the large internal surface area developed as a result of pore formation in crystalline SiC. The estimated density of trapped electrons per unit internal surface area, 5 × 10 12 cm -2 , is quite reasonable for the density of deep-level states at the SiC surface.
ABSTRACT A continuous glucose sensor employing radio frequency (RF) signals has been developed us... more ABSTRACT A continuous glucose sensor employing radio frequency (RF) signals has been developed using the biocompatible material Silicon Carbide (SiC). Unlike biosensors that require direct contact with interstitial fluids to trigger chemical reactions to operate, this biocompatible SiC sensor doesn't require a direct interface. The sensing mechanism is based upon a shift in resonant frequency as a function of change in glucose levels which electrically manifests itself as a change in blood permittivity and conductivity. For invivo applications the antenna sensor needs to operate inside the body environment, and it has been determined that the best operational location of this biocompatible SiC biosensor is within fatty tissue in close proximity to blood vessels. To test the sensor as a function of glucose level, measurements using synthetic body fluid (SBF), which is electrically equivalent to blood plasma, and pig blood were performed. Changes in sensor performance to varying glucose levels were measured and a shift in resonant frequency to lower values observed with increasing glucose level. In-vitro sensor performance demonstrated that the sensor showed a dose dependent response to glucose concentration from 120 mg/dl to 530 mg/dl. A shift of 40 MHz and 26 MHz for blood mimicking liquid and pig blood was observed corresponding to 97 KHz and 67 KHz shift per 1 mg/dl change in blood glucose.
Atomic layer deposited (ALD) Pb(Zr,Ti)Ox (PZT) ultra-thin films were synthesized on an ALD Al2O3 ... more Atomic layer deposited (ALD) Pb(Zr,Ti)Ox (PZT) ultra-thin films were synthesized on an ALD Al2O3 insulation layer on 4H-SiC substrate for metal-ferroelectric-insulator-semiconductor (MFIS) device applications. The as-deposited PZT was amorphous but crystallized into a perovskite polycrystalline structure with a preferred [002] orientation upon rapid thermal annealing (RTA) at 950 °C. The capacitance-voltage and current-voltage characteristics of the MFIS devices indicate carrier injection to the film induced by polarization and Fowler-Nordheim (FN) tunneling when electric field was high. The polarization-voltage measurements exhibited reasonable remanent and saturation polarization and a coercive electrical field comparable to that reported for bulk PZT. The piezoresponse force microscope measurements confirmed the polarization, coercive, and retention properties of ultra-thin ALD PZT films.
ABSTRACTWe report on the growth and crystal quality of CVD epitaxial layers grown on porous SiC (... more ABSTRACTWe report on the growth and crystal quality of CVD epitaxial layers grown on porous SiC (PSC) substrates. A layer of porous SiC was fabricated by surface anodization of commercial 4H and 6H-SiC (0001)Si face off-axis wafers. The 4H and 6H-SiC epilayers were grown on porous SiC (PSC) substrates using atmospheric pressure CVD at 1580°C and a Si to C ratio of 0.3. Results of X-ray diffraction, RHEED, SEM and AFM characterization demonstrated good surface quality of the films grown on porous material. PL data indicate a greatly improved defect structure in the epi layers grown on PSC as compared to control samples. Preliminary etch pit experiments to estimate the dislocation density indicate a three-fold reduction in defect density in the epi material grown on PSC substrates as compared to epi grown conventional substrates.
We have studied the electroreflectance (ER) spectra of n- and p-type 4H–SiC polytype samples from... more We have studied the electroreflectance (ER) spectra of n- and p-type 4H–SiC polytype samples from 3 to 6.5 eV. The fundamental band gap and higher lying critical points are measured at room temperature. For this polytype, we observe band-gap narrowing in one of the structures with higher doping concentration.
We report on non-contact and non-destructive spatially resolved characterization of traps and lum... more We report on non-contact and non-destructive spatially resolved characterization of traps and luminescence centers in vanadium-free semi-insulating 6H-SiC. Two optical techniques were employed: photoluminescence (PL) mapping and thermally stimulated luminescence (TSL) imaging on SiC wafers. PL and TSL topography reveal inhomogeneity at the periphery regions of the wafers. Low-temperature PL spectra show broad bands with the maxima at 1.75eV and 1.2eV, including a sharp zero-phonon line at 1.344eV. The TSL glow curves at T>80K show different peaks in the visible and infrared bands. The luminescence spectrum of the 105K TSL peak replicates 1.75eV band, while the 120K peak corresponds to the 1.2eV band. Additionally, the high temperature TSL peak at 210K shows an excellent match with 1.344eV zero phonon line. The trap energies of different peaks are calculated. We discuss a model of complex defects composed of closely spaced electron (hole) trap and UD3 defect.
Core–shell Si/SiC nanostructures appear as promising building blocks for sensing applications, th... more Core–shell Si/SiC nanostructures appear as promising building blocks for sensing applications, thanks to the high chemical stability of SiC coupled with the semiconducting properties of Si. In order to optimize the fabrication process of such structures, Si nanowires were coated with a thin SiC layer, and integrated as back-gated field-effet transistors. Two approaches for the fabrication of the SiC shell were then investigated. The first approach involves chemical vapor deposition of amorphous SiC on Si nanowires, without the need for masking; the second approach involves carbonization of Si surfaces to produce a thin crystalline SiC layer, but requires a larger thermal budget. The resulting structures were analyzed using high-resolution transmission electron microscopy (HR-TEM), and the devices were characterized electrically. Electrical characterization shows that the carbonization approach induces a dramatic decrease in drain-to-source current associated with gate leakage, whereas the electrical performances were preserved in the case of chemical deposition.
A 4H-SiC epitaxial growth process has been developed in a horizontal hot-wall CVD reactor using a... more A 4H-SiC epitaxial growth process has been developed in a horizontal hot-wall CVD reactor using a standard chemistry of silane-propane-hydrogen, producing repeatable growth rates up to 32 μm/h. The growth rate was studied as a function of pressure, silane flow rate, and growth time. The structural quality of the films was determined by X-ray diffraction. A 65 μm thick epitaxial layer was grown at the 32 μm/h rate, resulting in a smooth, specular film morphology with occasional carrot-like and triangular defects. The film proved to be of high structural quality with an X-ray rocking curve FWHM value of the (0004) peak of 11 arcseconds.
ABSTRACTPendeo Epitaxy is a type of Lateral Epitaxial Overgrowth (LEO) that instead of using a di... more ABSTRACTPendeo Epitaxy is a type of Lateral Epitaxial Overgrowth (LEO) that instead of using a dielectric buffer layer, uses an etched substrate to grow laterally without an interface layer. We report the first successful growth of 3C-SiC on Si using Pendeo epitaxy. Rectangular stripes of 3C-SiC on (100) Si substrates were fabricated, along both the [110] and [100] directions. Pendeo epi was only observed for columns parallel to [001], indicating a preferred growth facet for Pendeo epi of 3C-SiC on Si. SEM and TEM investigations were performed to assess the material quality of the Pendeo 3C-SiC material. Films were grown for 60 min at 1310°C and film coalescence was achieved without evidence of voids where the growth fronts joined. TEM data indicate not only the growth of vertical and lateral 3C-SiC on the 3C-SiC seed layer but direct nucleation of 3C-SiC on the exposed Si columns side wall and trench bottom, despite the lack of a carbonization procedure. The quality of the Pendeo 3C-SiC film appears to be of high quality indicating that Pendeo epi of 3C-SiC on low-cost, large-diameter Si substrates may prove to be a cost effective way to grow device-grade SiC layers on Si substrates for device applications.
Page 1. Photoluminescence and Thermally Stimulated Luminescence in Semi-Insulating SiC Yu. M. Sul... more Page 1. Photoluminescence and Thermally Stimulated Luminescence in Semi-Insulating SiC Yu. M. Suleimanov 1 , S. Lulu 1 , I. Tarasov 1 , S. Ostapenko 1 , VD Heydemann 2 , MD Roth 2 , O. Kordina 2 and MF MacMillan 2 andS. E. Saddow 1 . ...
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